JPWO2018105365A1 - Light guide plate, surface light emitting device, and method of manufacturing light guide plate - Google Patents

Abstract

The light guide plate of the present invention is a light guide plate having a scattering layer between two glass plates, in which the glass plate and the scattering layer are integrated, and the scattering layer is obtained by a stretching method. It is a film, The haze measured by the method based on JISK7136 of this light-guide plate is 0.2% or more, It is characterized by the above-mentioned. The light guide plate can be suitably used for an edge light type surface emitting device. Moreover, it is preferable that the said scattering layer is a transparent polyethylene terephthalate film obtained by the biaxial stretching method, and has an adhesive resin layer between the said glass plate and the said scattering layer.

Description

  The present invention relates to a light guide plate used in a surface light emitting device.

  2. Description of the Related Art Conventionally, surface light emitting devices have been used as electric signboards and displays, lighting fixtures for vehicles and buildings, and the like. There are two types of surface light emitting devices: a backlight method in which a light source is incident from a direction perpendicular to the light emitting surface and an edge light method in which the light source is incident from a substantially parallel direction. Therefore, the edge light system is widely adopted (see, for example, Patent Document 1).

  The edge light type surface light-emitting device uses an LED as a light source, and includes a light guide plate that propagates incident light in an in-plane direction and a light scattering plate that scatters incident light and emits light to the outside. The one used is widely known. Conventionally, transparent resins such as acrylic resin, polycarbonate, and polystyrene, and glass plates have been used as the light guide, and inks and paints having a scattering function have been widely used as the scattering part.

  Conventionally, there is a wide range of methods of using the light guide plate as described above as a single plate and printing ink or paint on the surface, or processing the surface of the single plate with a laser or the like to increase the surface scattering. It was used. However, there is a problem that the resin plate lacks chemical resistance, weather resistance, scratch resistance and the like.

  In order to solve the above problem, for example, in Patent Document 2, a resin plate provided with a light scattering paint or ink for scattering light on a surface between glass plates is integrated with an adhesive. A light guide plate is disclosed. In this document, a glass plate and a resin plate are used as the light guide part, and a paint or ink for light scattering is used as the scattering part, and transparent acrylic, polycarbonate, polyethylene terephthalate (PET) as the resin plate used as the light guide part, Examples include polypropylene (PP), cycloolefin polymer (COP), and urethane.

  Patent Document 3 discloses a surface-emitting laminated glass that is laminated and integrated in the order of a reflective film, a light guide plate, and a diffusion film between two glass plates. In this document, a light guide plate is used as the light guide portion, and a diffusion film is used as the scattering portion. The light guide plate propagates light by totally reflecting light on the front and back surfaces, such as highly transparent acrylic resin, etc. The resin material is illustrated. Examples of the diffusion film include a film having a light diffusion layer such as a binder resin and a light diffusing agent formed on the surface, and a film having a surface sandblasted, and a film to be used includes a PET film. Yes.

JP 2007-080531 A JP 2014-164989 A JP 2010-002442 A

  As mentioned above, conventional light guide plates using resin plates lack chemical resistance, weather resistance, scratch resistance, etc., so they are not suitable for outdoor use or in environments exposed to direct sunlight. There was a problem.

  Accordingly, an object of the present invention is to obtain a light guide plate using a glass plate that can be used in an edge light type surface light emitting device.

  According to the common knowledge of those skilled in the art, polyethylene terephthalate (hereinafter sometimes referred to as “PET”) has an excessively high scattering property inside, and therefore, it is considered that the light is scattered only near the light source and does not emit surface light. Further, in Patent Document 2 described above, PET is used as a transparent material for a light guide unit sandwiched between glass plates. In Patent Document 3 described above, a PET film is used as a diffusion film, and light diffusion is performed on the PET film. It has been disclosed that the above-described processing is performed.

  The present inventors made a laminated glass in which a PET film was sandwiched between two glass plates through a PVB film, and each layer was deaerated and integrated in a pressurized / heated environment, and the resulting laminated glass When the LED light source was irradiated from the end face, it was surprisingly found that surface emission occurred. As a result of further investigations, the above-described surface emission can be obtained with a laminated glass integrated with a PET film sandwiched without coating or mixing light scattering paint or ink on the PET film. I found out that That is, it was newly found that the PET film functions as a scattering portion by using the above laminated glass.

  When the optical characteristics of the obtained laminated glass were measured, it was found that any laminated glass having a haze value of 0.2% or more can be used as a light guide plate. Moreover, the haze value of the film before making laminated glass showed a value higher than the haze value after making laminated glass. The mechanism of the occurrence of surface emission is unknown, but from the obtained knowledge, for example, it can be considered as follows. The used PET film is a transparent film prepared by a stretching method, and it is generally known that a polymer obtained by a stretching method is oriented with a polymer contained in the film by a stretching process. Since the oriented film is considered to be polarized, it is considered that light was scattered due to the polarization characteristics of the film. Furthermore, as described above, by degassing and integrating each layer, the haze on the film surface was reduced, excessive scattering was suppressed, and it was thought that surface emission occurred not only in the vicinity of the light source. It is done.

  That is, the first invention is a light guide plate having a scattering layer between two glass plates, the glass plate and the scattering layer being integrated, and the scattering layer is obtained by a stretching method. It is a resin film, and is a light guide plate having a haze of 0.2% or more measured by a method according to JIS K7136 of the light guide plate.

  Further, the second invention is a step of laminating a transparent resin film obtained by a stretching method and a second glass plate in this order on a first glass plate, and forming a laminate, and each layer of the laminate is It is the manufacturing method of the light-guide plate which has the process of deaeration and the process of integrating this laminated body after deaeration.

  According to the present invention, it is possible to obtain a light guide plate using a glass plate that can be used in an edge light type surface light emitting device.

It is a simplified diagram explaining the upper side of this specification, a lower side, a width | variety, and the thickness direction. It is a cross-sectional schematic diagram showing one Embodiment of this invention. It is the cross-sectional schematic diagram which shows the light guide of (a) surface emission and (b) comparative form of one Embodiment of this invention. It is a figure which shows the luminance distribution at the time of the surface light emission of (a) Example 3 and (b) comparative example 2, respectively. It is a cross-sectional schematic diagram showing one Embodiment of this invention.

1: Explanation of Terms In this specification, as shown in FIG. 1, the side on the light source 1 side of the light guide plate 10 is the lower side 11, and the side farthest from the light source 1 is the upper side 12. The direction from the lower side 11 to the upper side 12 is the Y direction, the direction parallel to the lower side 11 and the upper side 12 is the X direction, and the thickness direction of the glass plate G, the adhesive resin layer 2 and the scattering layer 3 is the Z direction. The length of the ten glass plates G in the X direction is defined as the width of the light guide plate. The XZ plane and the YZ plane are end faces.

(Haze)
The haze of this specification uses the value measured by the method based on JISK7136. The measurement was performed using a haze meter (HZ-T, manufactured by Suga Test Instruments). Moreover, when measuring the haze of a light-guide plate, the glass plate to be used was made into 2 mm thick soda-lime glass.

(Luminance)
In this specification, the luminance (cd / m ² ) near the center in the width direction was measured 20 mm from the lower side of the light guide plate using a 2D color luminance meter (Topcon Technohouse, UA-200A).

(Transparent)
In this invention, the transparent resin film obtained by the extending | stretching method is used for a scattering layer. The “transparent” means that the total light transmittance of the film before being integrated as a light guide plate is 80% or more. Moreover, the total light transmittance in this specification was measured using the haze meter mentioned above.

2: Light Guide Plate A preferred embodiment of the first invention and an application example thereof will be described below with reference to FIGS. Further, the present invention is not limited to the embodiment.

  A preferred embodiment of the present invention is a light guide plate 10 having a scattering layer 3 between two glass plates G, and the glass plate G and the scattering layer 3 are integrated by an adhesive resin layer 2. The scattering layer 3 is a transparent resin film obtained by a stretching method, and the light guide plate 10 has a haze of 0.2% or more measured by a method according to JIS K7136 of the light guide plate 10.

(Glass plate G)
As the glass plate G, a commercially available glass plate can be used, and is not particularly limited. For example, general things, such as float glass, what processed the glass plate, such as tempered glass and bending glass, etc. are mentioned. Further, as the composition of the glass plate G, glass having a highly transparent composition such as soda lime glass or highly transmissive glass is preferable, but colored glass may be used as long as it does not excessively absorb visible light.

  The thickness of the glass plate G to be used is not particularly limited. For example, it is good also as the thickness (1-25 mm) grade used for the object for general vehicles or construction. Moreover, when using for vehicles, since the request | requirement to the weight reduction of a vehicle body is increasing in recent years, it is preferable to set it as about 1-5 mm. For example, you may use the sheet glass less than 1 mm.

  If the light emission of the light guide plate 10 is not hindered, various kinds of materials such as an infrared absorption film, an infrared reflection film, an ultraviolet absorption film, an ultraviolet reflection film, a colored film, a visible light reflection film, and an antireflection film are formed on the surface of the glass plate G. A film or the like may be formed.

(Adhesive resin layer 2)
The adhesive resin layer 2 is particularly limited as long as the difference in refractive index from the glass plate G is less than 0.1, the glass plate G and the scattering layer 3 can be integrated, and coloring or the like does not occur during heating. It is not a thing. Examples of the resin include polyvinyl butyral (hereinafter sometimes referred to as “PVB”) resin, ethylene-vinyl acetate copolymer (hereinafter sometimes referred to as “EVA”) resin, and cycloolefin polymer. It is preferable to include at least one selected from the group consisting of a resin, a polyurethane resin, an acrylic resin, an ionomer resin, and a thermoplastic elastomer. Moreover, since the workability is good when a thermoplastic resin having a film shape is used at room temperature, among them, PVB resin and EVA resin are particularly preferably usable. If the transparent resin film and the glass plate G can be integrated, the adhesive resin layer 2 may not be used.

  The adhesive resin layer 2 may have a sound insulation function, a heat insulation function, a heat insulation function, high elasticity, or the like as necessary. For example, PVB resin with improved sound insulation, PVB resin having an infrared absorber inside, high-elasticity PVB resin, low-elasticity PVB resin, wedge-shaped PVB resin with a gradient in thickness, and the like can be given. Moreover, you may use what overlapped two or more types of different resin.

(Scattering layer 3)
As the scattering layer 3, a transparent resin film obtained by a stretching method as described above is used. The stretching method is a process mainly performed for adjusting the thickness of the film, and is a method of performing stretching in a uniaxial direction or a biaxial direction while heating at a predetermined temperature. It is considered that the transparent resin film comes to scatter because orientation occurs inside the film by stretching. Examples of the transparent resin film obtained by the stretching method include PET film, PEN film, polybutadiene terephthalate film, nylon film, polypropylene film, and polystyrene film. Further, as long as light emission is not hindered, it may have a sound insulation function, particles having a function of absorbing and reflecting infrared rays, ultraviolet rays, and the like, or may have the above functional film on the surface. .

  The scattering layer 3 is preferably a transparent polyethylene terephthalate film obtained by a biaxial stretching method. The film obtained by the biaxial stretching method is expected to have a stronger orientation, and it is considered that light is more easily scattered. In the case of a PET film, an opaque PET film having a high degree of crystallization in order to have a scattering function and a transparent PET film in which crystallization is suppressed and transparency is maintained are commercially available. For surface emission, it is necessary to scatter and propagate incident light, and the latter transparent PET film is preferably used.

  Further, the transparent resin film is preferable because it is considered that the surface emission can be further improved by making the refractive index larger than that of the glass plate G and the adhesive resin layer 2. In particular, when the refractive index difference between the glass plate G and the adhesive resin layer 2 is less than 0.1, it is considered that refraction and reflection are more likely to occur when the refractive index difference between the transparent resin film and the adhesive resin layer 2 is larger. .

  Moreover, although the thickness of a transparent resin film is not specifically limited, For example, if it is about 30-300 micrometers, workability | operativity is preferable. In addition, if the thickness of the transparent resin film is increased, the scattering layer 3 is increased and surface emission is considered to be improved. Therefore, if integration is possible, the thickness may exceed 300 μm.

  The scattering layer 3 of the present invention may be a layer that intentionally does not contain light scattering paint and ink inside and on the surface. Since the scattering layer 3 is considered to be scattered due to the orientation of the transparent resin film, it is possible to obtain surface light emission without intentionally adding a light scattering component.

  A transparent resin film having a haze of 0.2% or more after the light guide plate 10 is used is used. When the present inventors examined, it turned out that the haze value of the light-guide plate 10 tends to become lower than the haze value when a transparent resin film is measured alone. This is because before the light guide plate 10 is obtained, the value obtained by combining the surface haze of the transparent resin film and the internal haze of the film is obtained. After the light guide plate 10 is formed, the surface adheres to the adhesive resin layer 2. This is probably because the surface haze is reduced and the internal haze is mainly obtained. Therefore, it is desirable to use a transparent resin film having a high internal haze.

  Here, it is difficult to measure only the internal haze of the transparent resin film in advance, and it is difficult to determine which transparent resin film is suitable unless it is actually integrated. Therefore, when the light guide plate 10 exhibiting good surface light emission was examined, for example, when a film having a tendency that the haze value of the film increases as the thickness of the transparent resin film increases, the light guide plate is used. It was found that even after setting to 10, the haze tends to show a high value. In addition to the above, even in the case of a transparent resin film having a small correlation, for example, by increasing the thickness, the haze value of the light guide plate 10 can be set to 0.2% or more.

  Moreover, the area of the transparent resin film may be the same as the area of the glass plate G facing or smaller than the area of the glass plate G. In addition, when the glass plate G has a curved surface, wrinkles may occur in the peripheral portion of the transparent resin film that overlaps the peripheral portion of the glass plate G in an attempt to follow the curved shape of the glass plate during integration. . In that case, by using a transparent resin film having an area smaller than that of the glass plate G so that the peripheral portion of the glass plate G and the transparent resin film do not overlap, Can be suppressed, which is preferable. Moreover, it is not restricted to the peripheral part of this transparent resin film, You may divide | segment into several sheets as needed, and may use the cut-out transparent resin film.

  Two or more transparent resin films may be laminated and used. In that case, it is preferable that the transparent resin film and the transparent resin film are integrated by various adhesives or physical adsorption. Further, a transparent film having additional functionality may be sandwiched between the transparent resin film and the transparent resin film, and may be integrated via an adhesive or the like. Examples of the transparent film having the above functionality include a light control film, a liquid crystal film, and a heat shielding film. In addition, a single transparent resin film and a transparent film having the above-mentioned functionality may be laminated without being sandwiched between transparent resin films, and the transparent film having two or more functionalities may be laminated. A transparent resin film may be sandwiched.

(Binder layer 4)
When the light guide plate 10 is formed using the transparent resin film and the adhesive resin layer 2, in order to prevent separation or destruction when a strong external force is applied, for example, as shown in FIG. It is preferable to improve the adhesive force by using the binder layer 4 that assists the adhesion between the transparent resin film and the adhesive resin layer 2. The binder layer 4 is in contact with the surface of the transparent resin film and the surface of the adhesive resin layer 2 so that the light guide plate 10 can be more integrated to make separation and destruction difficult. That is, it is preferable to have a binder layer 4 between the transparent resin film and the adhesive resin layer 2, and the binder layer 4 is in contact with the transparent resin film and the adhesive resin layer 2.

  The binder layer 4 may be any layer that can be adhered or adhered to both the transparent resin film and the adhesive resin layer 2 and may not be a visible film or layer. For example, a general transparent adhesive can be used. Moreover, the functional group (for example, a hydroxyl group, a carbonyl group) which can be couple | bonded with the surface of said transparent resin film and the adhesive resin layer 2 by giving a silane coupling process or a plasma process to the surface of the transparent resin film or the adhesive resin layer 2 , Amino groups, etc.) are preferably generated on the surface of the binder layer 4 because workability is good. Further, the adhesive strength is improved if the binder layer 4 is formed on at least one surface of the transparent resin film, but it is more preferable that the binder layer 4 is formed on both surfaces of the transparent resin film. When the binder layer 4 is formed on both surfaces of the transparent resin film, the difference in adhesive force between the surfaces of the transparent resin film can be reduced, so that local peeling or the like can be suppressed.

  What is necessary is just to select what can adhere | attach a transparent resin film and the adhesive resin layer 2 as said silane coupling material, It does not specifically limit. For example, a silane coupling material having an amino group, an epoxy group, a vinyl group, a methacryl group, an acrylic group, an isocyanate group, or the like can be used. For example, when a PET film is used as the transparent resin film and a PVB resin is used as the adhesive resin layer 2, it is preferable to use a silane coupling material having an amino group. Examples of the silane coupling material include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and N- (2-aminoethyl) -3-aminopropyltrimethoxysilane.

(Light guide plate 10)
As described above, the light guide plate 10 of the present invention has a haze measured by a method according to JIS K7136 of 0.2% or more, and exhibits surface emission. Moreover, although an upper limit is not specifically limited, For example, it is good also as 10% or less.

  As shown in FIG. 2, the light guide plate 10 has the adhesive resin layer 2 between the glass plate G and the scattering layer 3, and the glass plate G and each layer are preferably integrated. . Also, if the surface emission is not significantly impaired, it has an arbitrary layer or particle in each layer or each layer for the purpose of improving the adhesion between the layers or improving the luminance of the surface emission. Also good.

  Moreover, the adhesive resin layer 2 may not be provided between the glass plate G and the scattering layer 3 as long as it can be integrated in a state where the layers are deaerated. For example, in the state where the glass plate G surface and the scattering layer 3 surface are physically adsorbed or adhered, or between the glass plate G and the scattering layer 3 is deaerated, a separate fixing member is attached and integrated. Also good.

  In a preferred embodiment, the total light transmittance of the light guide plate 10 may be 70% or more. In the present invention, since the transparent resin film is used as the scattering layer 3, the obtained light guide plate 10 can also have transparency. The transparency is preferable because it is useful for various window members and displays, transparent panels for indoor and outdoor decoration, and the like.

(Surface emitting device)
One of the preferred embodiments of the present invention is a surface light emitting device having the light guide plate 10 and a light source 1 capable of entering light from an end face of the light guide plate 10 as shown in FIG. It is. At this time, the light source 1 is not particularly limited, but it is preferable to use an LED light source because the present invention can perform scattering and light propagation even if the LED light source travels straight. Note that the light guide plate 10 of the present invention can scatter light regardless of whether it is incident obliquely or incident on the XY plane.

  As shown in FIG. 3A, the incident light incident on the light guide plate 10 generates propagation light propagating through the light guide plate 10 and scattered light scattered by the scattering layer 3, thereby obtaining surface light emission. It is thought that. Further, it is considered that the propagating light propagates in the Y direction in the figure due to total reflection between the atmosphere and the glass plate G. In addition, as shown in FIG. 3B, since the total reflection mainly occurs when the scattering layer 3 is not provided, surface emission cannot be obtained.

3: Manufacturing method of light guide plate The second invention is described below. The present invention includes a step of laminating a transparent resin film obtained by a stretching method and a second glass plate on a first glass plate in this order to form a laminate, and a step of degassing each layer of the laminate. And a step of integrating the laminated body after deaeration.

  In one preferred embodiment of the present invention, the step of forming the laminate includes, in order, a first adhesive resin film, a transparent resin film obtained by a stretching method, and a second adhesive resin on the first glass plate. It is the manufacturing method of the light-guide plate which is a process of laminating | stacking a film and a 2nd glass plate, and forming a laminated body. When the adhesive resin film is used as described above, the step of integrating the laminate is a step of heating the laminate after deaeration in a pressurized environment and integrating the laminate. Further preferred. The present embodiment will be described below. In addition, this invention is not limited to the following embodiment.

  First, a first adhesive resin film, a transparent resin film obtained by a stretching method, a second adhesive resin film, and a second glass plate are sequentially laminated on the first glass plate to form a laminate. At this time, each film may be sequentially laminated, or a laminated film obtained by previously laminating and integrating each film may be used.

  Next, each layer of the laminate is degassed. An existing method may be used for the deaeration process. For example, a tube made of a rubber-based resin is attached to the periphery of the laminated body, and air is exhausted from the exhaust nozzle to deaerate, or in a vacuum bag. Examples include a method of deaeration by putting the laminate and exhausting air from an exhaust nozzle, and a method of degassing each layer by applying pressure so that the laminate is sandwiched between a pair of rolls.

  Next, the laminated body is heated under a pressurized environment, and the laminated body is integrated to obtain a light guide plate. In this step, it is convenient and preferable to use a general-purpose autoclave. In the case of using an autoclave, the pressure and temperature are appropriately selected according to the adhesive resin film or the transparent resin film, and integration is performed. For example, when PVB resin or EVA resin is used for the adhesive resin film and PET film is used for the transparent resin film, the temperature is increased until the maximum temperature is within the range of 80 to 150 ° C. The above integration is possible by maintaining the vicinity of the temperature. At this time, pressurization is performed so as to be within a pressure range of 0.9 to 1.5 MPa. Either pressurization or heating may be performed first or simultaneously. Moreover, you may pressurize from the middle of a heating process. In addition to the autoclave, a heatable press or the like may be used.

  Moreover, when not using an adhesive resin film, as above-mentioned, you may physically adsorb | suck or adhere the glass plate G surface and the scattering layer 3 surface using various presses. Further, a fixing member may be separately attached and integrated with the glass plate G and the scattering layer 3 being deaerated.

  Moreover, it is preferable to have a step of forming the binder layer 4 on the surface of the transparent resin film before laminating the transparent resin film. By passing through this step, it is possible to laminate the first adhesive resin film and the second adhesive resin film in a state where the binder layer 4 is formed on the surface of the transparent resin film.

  As a method for forming the binder layer 4, when a PVB resin is used as the adhesive resin film, it is preferable to apply a silane coupling material having an amino group to the surface of the transparent resin film. As the coating method, known coating methods such as gravure coating, roll coating, die coating, bar coating, dipping, spray coating, and spin coating can be used. In particular, it is preferable to use a gravure coating that can use a roll-to-roll method capable of forming a thin layer at high speed.

  For example, when a PET film is used as the transparent resin film and a PVB resin is used as the adhesive resin layer 2, it is preferable to use a silane coupling material having an amino group. Examples of the silane coupling material as described above include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and N- (2-aminoethyl) -3-aminopropyltrimethoxysilane. When using the said silane coupling material, after apply | coating to the PET film surface using the said coating method, it is made to dry and the layer of a silane coupling material is formed. Next, in order to react the silane coupling material and the surface of the PET film, the binder layer 4 is obtained by holding for a predetermined time (for example, at room temperature to 60 ° C. for 3 days to 10 days). The thickness of the binder layer 4 obtained by the coating method as described above is not particularly limited, but may be about 0.5 μm to 10 μm.

  Further, the surface of the transparent resin film may be subjected to plasma treatment. When high-energy electrons or ions are applied to the transparent resin film by plasma treatment, a highly reactive functional group such as a carboxyl group, a hydroxyl group, an amino group, or a carbonyl group may be newly generated near the surface of the transparent resin film. It becomes possible. The functional group is different depending on the atmospheric gas used during the plasma treatment, and may be appropriately selected according to the transparent resin film or the adhesive resin layer 2. For example, argon, helium, nitrogen, oxygen, air, carbon dioxide, water vapor Etc. can be used. The plasma treatment may be performed in a vacuum or at atmospheric pressure. For example, when a PET film is used as the transparent resin film and a PVB resin is used as the adhesive resin layer 2, the plasma treatment is performed for about 30 seconds to 3 minutes for an A4 size PET film using a plasma irradiation surface modification device in atmospheric pressure. It is possible to form the binder layer 4 on the surface of the PET film.

  Below, the Example and comparative example of this invention are shown. The present invention is not limited to the following.

As the glass plate, a soda lime glass plate (about 300 mm × 210 mm, thickness 2 mm) obtained by the float process was used. Moreover, as the adhesive resin layer, a PVB resin film (thickness 0.38 mm) was used. Moreover, as the transparent resin film, the following biaxially stretched PET films A to E were used. Moreover, each transparent resin film measured haze before preparation of a light-guide plate.
A: Ultra high transparency polyester film (Toyobo; Cosmo Shine A4300, thickness 50 μm)
B: Ultra-high transparency polyester film (Toyobo; Cosmo Shine A4300, thickness 125 μm)
C: Polyester film (Toray; Lumirror T60, thickness 50 μm)
D: Polyester film (manufactured by Toray; Lumirror T60, thickness 188 μm)
E: Polyester film (manufactured by Toray; Lumirror U34, thickness 50 μm)

[Examples 1 to 4, Comparative Example 1]
First, a PVB resin film, a biaxially stretched PET film, a PVB resin film, and a glass plate were laminated in this order on a glass plate to obtain a laminate. Next, the laminate was placed in a vacuum bag, and air was exhausted from the exhaust nozzle to degas each layer. Next, the laminate was placed in an autoclave and subjected to pressure and heat treatment to obtain each sample. At this time, the temperature was set to 135 ° C., the pressure was set to 1 MPa, and the treatment time was 30 minutes. Next, haze, total light transmittance, and luminance were measured for the obtained samples by the following methods.

[Comparative Example 2]
A sample was obtained in the same manner as in Example 1 except that a 300 mm × 300 mm, 2 mm thick glass plate was used and no transparent resin film was used, and haze, total light transmittance, and luminance were measured.

(Measurement of haze and total light transmittance)
The haze of each transparent resin film, the haze of each obtained sample, and the total light transmittance were measured using a haze meter (manufactured by Suga Test Instruments Co., Ltd., HZ-T) in accordance with JIS K7136. The values obtained are listed in Table 1. In addition, the haze of the transparent resin film was described as “film”, and the haze of the sample was described as “light guide plate”.

(Measurement of brightness)
First, each obtained sample was installed on the light emission part of tape LED (the Elpara 5050 tape LED8142). At this time, the end surface (XZ surface) of the sample was brought into contact with the tape LED, and LED light (white) was incident from the end surface.
Next, the luminance (cd / m ² ) of the surface emission of the XY plane of each sample was measured using a 2D color luminance meter (manufactured by Topcon Technohouse, UA-200A). The measurement was performed in a dark room, the distance between the sample and the 2D color luminance meter was 800 mm, the measurement point of the sample was 20 mm from the lower side of the light guide plate, and the vicinity of the center in the width direction. The values obtained are listed in Table 1.

  From the above, it was found that in Examples 1 to 4, the haze of the light guide plate was 0.2% or more, and even when compared with Comparative Example 2 having no transparent resin film, the luminance was high. 4A shows the luminance distribution of a 2D color luminance meter (manufactured by Topcon Technohouse, UA-200A) at the time of surface light emission of Example 3. FIG. As shown in the figure, surface emission was actually confirmed.

  On the other hand, Comparative Example 1 had a haze of 0.1%, and the luminance was the same as Comparative Example 2. Further, with respect to the surface emission when light is incident on the end face of Comparative Example 2, the luminance distribution was measured in the same manner as in Example 3 and shown in FIG. As a result, it was found that no surface emission was observed in Comparative Example 2.

  In Examples 1 to 4 and Comparative Example 1, the haze of the light guide plate was lower than the haze in the film state before making the light guide plate. This is presumably because the surface haze of the film was lowered by becoming a light guide plate as described above.

G: Glass plate
1: light source
2: Adhesive resin layer,
3: scattering layer,
4: Binder layer
10: Light guide plate,
11: Lower side,
12: Upper side

Claims (14)

A light guide plate having a scattering layer between two glass plates, the glass plate and the scattering layer being integrated;
The scattering layer is a transparent resin film obtained by a stretching method,
The light guide plate whose haze measured by the method based on JISK7136 of this light guide plate is 0.2% or more. The light guide plate according to claim 1, wherein the scattering layer is a transparent polyethylene terephthalate film obtained by a biaxial stretching method. The light guide plate according to claim 1, further comprising an adhesive resin layer between the glass plate and the scattering layer. The light guide plate according to claim 3, wherein the adhesive resin layer includes at least one selected from the group consisting of polyvinyl butyral resin, EVA resin, cycloolefin polymer resin, polyurethane resin, and acrylic resin. Having a binder layer between the transparent resin film and the adhesive resin layer;
The light guide plate according to claim 3 or 4, wherein the binder layer is in contact with the transparent resin film and the adhesive resin layer. The light guide plate according to claim 1, wherein the light guide plate has a total light transmittance of 70% or more. A surface light-emitting device comprising: the light guide plate according to claim 1; and a light source capable of entering light from an end face of the light guide plate. The surface light-emitting device according to claim 7, wherein the light source is an LED light source. A step of laminating a transparent resin film obtained by a stretching method and a second glass plate in this order on the first glass plate, and forming a laminate,
The manufacturing method of the light-guide plate which has the process of deaerating each interlayer of this laminated body, and the process of integrating this laminated body after deaeration. The step of forming the laminate includes sequentially laminating the first adhesive resin film, the transparent resin film obtained by the stretching method, the second adhesive resin film, and the second glass plate on the first glass plate. The method of manufacturing a light guide plate according to claim 9, wherein the method is a forming step. The step of integrating the laminate is a step of heating the laminate after deaeration in a pressurized environment to integrate the laminate. Manufacturing method of the light guide plate. The method for producing a light guide plate according to claim 10 or 11, further comprising a step of forming a binder layer on a surface of the transparent resin film before the transparent resin film is laminated. The method for manufacturing a light guide plate according to claim 9, wherein the transparent resin film is a transparent polyethylene terephthalate film obtained by a biaxial stretching method. The method for manufacturing a light guide plate according to any one of claims 9 to 13, wherein in the step of integrating the laminates, heating is performed within a range of 80 to 150 ° C.

Images